1. Field of the Invention
The present invention relates to a combustion prediction and discrimination apparatus for an internal combustion engine for predicting burning conditions by calculations based on one portion of the cylinder pressure information, as well as a control apparatus using the combustion prediction and discrimination apparatus.
2. Related Art
For conventional burning condition discrimination apparatuses, apparatuses utilizing a knock sensor, a cylinder pressure sensor, an ion gap sensor and an O.sub.2 sensor have been widely used.
The knock sensor used for detecting vibration due to knocking is normally attached to the internal combustion engine cylinder block to detect the pressure vibrations accompanying the occurrence of knocking as vibration of the cylinder wall. However, in case of using this type of knock sensor, the knocking can not be discriminated to have occurred until the cylinder block vibrates abnormally due to the occurrence of knocking. Therefore, it is impossible to predict the occurrence of knocking from data related to the initial combustion stage.
With the cylinder pressure detection sensor technique for detecting the cylinder pressure vibrations accompanying knocking (Japanese Patent Application Laid-Open No. 61-13126), knocking can be discriminated to have occurred only after the sudden occurrence of cylinder pressure vibrations. Thus, the occurrence of knocking cannot be predicted before the occurrence of knocking.
Also, the technique for detecting misfire using the cylinder pressure detection sensor (Japanese Patent Application Laid-Open No. 62-30932) has the following difficulty. If, after ignition, the flame spreads and then the flame growth stops to cause misfire, it will be difficult to discriminate misfire since the cylinder pressure before misfire resembles that of the normal burning.
Further, when detecting misfire by the ion gap sensor, the general technique is to have the sensor disposed inside the combustion chamber and to discriminate misfire based on whether or not the flame has reached a predetermined position within a predetermined time after spark ignition. However, in case of using the ion gap sensor, misfire is discriminated only when the flame has not reached the predetermined position in the predetermined time. Therefore, misfire cannot be predicted from combustion data of the initial burning period. Moreover, when the flame is stratified in one region of the combustion chamber, then, depending on the position of attachment of the sensor, it becomes impossible to detect the occurrence of misfire in some cases.
Still further, the O.sub.2 sensor which measures the air/fuel ratio of the internal combustion engine, is normally fitted to the engine exhaust pipe and by detecting the oxygen concentration in the exhaust gas the air/fuel ratio at the time of burning can be discriminated. However, when using the O.sub.2 sensor, it becomes possible to discriminate the air/fuel ratio only after the burning is finished and the exhaust gas is exhausted in the exhaust pipe. Further, since the response speed of the O.sub.2 sensor is slow, it is impossible to discriminate the air/fuel ratio before one burning cycle is finished or immediately thereafter. Moreover, in the case of application to multi-cylinder engines, it is impossible to discriminate each of the air/fuel ratios of the different cylinders independently.
As stated above, in the conventional technology, since there is either a problem of the validity and responsiveness of the burning condition sensor itself, or a problem with signal processing methods, the burning conditions of the cycle are discriminated by measuring the burning conditions over one complete burning period, either from the time of completion of burning or from the first occurrence of abnormal burning.
Accordingly the problem with the conventional technology is that it is impossible to predict the following burning conditions from the data of a portion of the burning within one cycle.